Manufacture of piezoelectric oscillator blanks



Aug. 14, RAMSAY MANUFACTURE OF PIEZO-ELECTRIC OSCILLATOR BLANKS FiledApril 21, 1943 6 Sheets-Sheet l INVENTOR MARCOS EAMM Y.

Y Q 3/ M A TONEY ELECTRIC OSCILLATOR BLANKS Filed April 21,

M. RAMSAY 1943 6 Sheets-Sheet 2 Aug. 14, 1945.

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MANUFACTURE OFPIEZO-ELECTRIC OSCILLATOR BLANKS Filed April 21, 1943 6Sheets-Sheet 3 INVENTOR flkwcu: AA WH 4 Aug. 14, 1945. M. RAMSAY2,382,257

MANUFACTURE OF PIEZO-ELECTRIC OSCILLATOR BLANKS Filed April 21 1943 6Sheets-Sheet 4 n \NVENTOR ffA/m J 16/4/ 714 )4 l 1 ATT I LJEY Aug. 14,1945. A Y 2,382,257

MANUFACTURE OF PIEZO-ELECTRIC OSCILLATOR BLANKS Filed April 21, 1943 6Sheets-Sheet 5 aiul lg A INVENTOR #46605 RAMJAK gig ATT RNEY mechanical(Y) axes of crystal.

Patented Aug. 14, 1945 MANUFACTURE OF rmzounaorarc OSCILLATOR BLANKSMarcus Ramsay, Great Neck, N. Y., assignor of eighteenand'three-fourthsper cent to Albert Ramsay, eighteen and three-fourths per cent to EricG. Ramsay, twenty-five per cent to H. Dorsey Spencer, all of New York,N. Y., and

- eighteen and three-fourths Young, Eugene, Oreg.

Application April 21,'1943, S eralNo. 483,906

(01. SIT-3) I 13 Claims. This invention relates to the cutting frombars,

sections, lumps or boulders of quartz, or other suitable crystals ofaccurately oriented blanks for use in the manufacture of oscillatorsor-res'i onators, such, for example, as those which are used in radiotransmission apparatus. Although the invention is applicable to thecutting of blanks from other crystals which exhibit the phenomenon ofpiezo-electricity, for convenience it will be hereinafter described inits application to quartz since quartz is the material most commonlyused for piezo-electric oscillators or resonators. As is well known, thefrequency characteristics of quartz oscillators or resonators, such asthose used in metering the wave bands of radio transmission sets, aredependent to a large extent upon the position of the quartz plate in theoriginal quartz crystal. In order that the resonator or oscillator mayeffect uniform con-- trol of the wave band of a radio transmitter undervarious climatic conditions and, particularly, in order that itsfrequency may not vary too much over a comparatively wide range oftemperatures, it is important that the blank from which the resonator oroscillator is made be so cut that its faces bear certain definiteangular relations to the optical (Z), electrical (X) and the originalquartz Cutting of such blanks from bars, sections, lumps or boulders'ofquartz, as heretofore practiced, has resulted in considerable waste ofmaterial because the cutting methods and the apparatus employed have notpermitted the maintenance of the orientation throughout the cuttingoperations. Not only has there been much waste of the raw material, butthere has also been an even greater waste of time and labor in checkingand correcting the errors in orientation brought about by the crudecutting methods and equally crude cutting apparatus heretofore employed.This has not been so important in the past, since supplies of crudematerial have been adequate to meet the heretofore existing demand.However, because of the now more extensive use of quartz oscillators andresonators, particularly in the radio transmission field, sup: j pliesof quartz suitable for the making of such oscillators or resonators havediminished, the cost of the raw material has markedly increased, and itis therefore important, both for economy of material and economy of timeand labor, to in-- sure as accurate an orientation as possible of'tals-sometimes called boulders.

per cent to W. Ford each blank produced at the time the bar or boulder;

A general object of the present invention, therefore, is to provideimproved methods and improved means for insuring the maintenance of theoriginal orientation of the quartz, from which oscillator or resonatorblanks are to be cut, throughout the successive-cutting operationsrequired to produce the blanks, particularly when it is cut fromproceeding by the more usual method of first cutting the lump or boulderinto sections, then cutting the sections into bars and then cutting theblanks from the bars, the invention aiming likewise to insure themaintenance of the orientation when wafers of blank thickness dimensionsare cut directly from the original lumps or boulvders. In the co-pendingapplication of W. Ford.

Young, Serial No. 479,609, filed March 18, 1943, has been disclosed animproved process and apparatus for quickly and accurately orientingquartz or other crystals, either face or rough, that is, quartz or othercrystal which either has some of its original crystal faces or which isin the form of broken or eroded fragments of crys-. The apparatusemployed in practicing the said Young process preferably comprises auniversal holder of such strength and rigidity and so mounted upon aremovable slide or carrier that it can be transferred from the orientingapparatus to a cutting machine and serve as a jig or work holder forholding the work in proper cutting relation to the saw. However, thesaws used in cutting either sections or wafers from rough lumps orboulders of quartz or from face crystals are usually metal diskshavingtheir peripheral edges and margins impregnated with small diamondparticles of sizes ranging from what may properly be called diamond dustup to 40 mesh or less. .In order thattoo much of the quartz may not bewasted in the kerf made by the saw, the cutting edges of these saws arerelatively thin, for example in the neighborhood of ,4 thick, the diskbeing usually slightly thinner to provide some clearance or set for thesaw. Even quartz cutting saws in which the diamonds are embedded in adisk produced by powder metallurgy have more or less the samecharacteristics,

a sufi'icient diameter to handle a fair-sized lump or boulder, isoperating at its rated cutting speed there will be some slight tendencyfor the saw not to cut in an absolute plane but tolead off in onedirection or the other and thus leave both the face of the blank severedfrom the bar or boulder and the face of the bar or boulder itself inplanes slightly inclined to the desired planes for said faces. Althoughsuch deviations of the cuts from the desired planes do not tend tobecome cumulative, if the work holder be sufficiently rigid and theinitial orientation be sufficiently accurate, it will be seen that ifnothing is done to correct the error thus produced both faces of eachblank will be inclined to the desired planes of such faces and both willhave to be corrected. In order to do this it will be necessary to orienteach blank'again. Such orientation may have to be effected several timeswhile correcting the blank, provided the first correction made upon oneof the faces does not completely restore it to the desired plane. Ofcourse, when one face has been properly corrected, then the other facemay be corrected with reference to that by bringing it into parallelismthereto. Such corrections, however, require not only considerable timeand labor but also considerable skill.

An important object of the present invention is to provide a process andmeans for practicing the process of cutting the blanks which willobviate entirely any necessity for subsequent orientation of any exceptpossibly the initial blank cut from a bar. To this end the presentinvention contemplates so effecting the cutting operations that eachblank as it is severed from the bar or boulder will have one true face,that is, a face lying absolutely in the desired plane or, in otherwords, lying in a plane making the desired angle to the optical (Z) axisand having the other axes to be considered, that is, an electrical (X)axis and a mechanical (Y) axis also in the desired relations to saidtrue face.

An important feature of the invention is the restoration to the bar orboulder, after each cut, of a face,to form one face of the succeedingblank or wafer, which lies in the desired plane of inclination andrelation to the aforementioned various axes of the bar or boulder.

A further important feature of the invention is a novel combined saw andsurface grinder in which these parts are so concentrically arranged andmounted that, after the bar, section, or boulder has been cut, the faceof the bar, section or boulder from which the blank, wafer, bar orsection has been cut will, in its further travel, pass over theconcentric surface grinder mounted on the same shaft or spindle. In thismanner extensive travel of the work holder in respect to the cutting andsurfacing tools is eliminated and difficulty in maintaining them intheir proper alignment in substantially the same plane is avoided.

Another important feature of the invention is the provision of meansassociated with a work holder in the blank cutting machine for effectingquickly and accurately such slight adjustment of this holder as may benecessary to compensate for any error growing out of transfer of theoriented bar to the holder, thus permitting such an adjustment, afterthe checking of an initial blank cut from a bar, as will insure that allsubsequent blanks are positively oriented.

The invention also contemplates the provision of means for quickly andaccurately bringing into operative position the abrading surface of thesurface grinder when wear has so reduced said surface that it does notproject sufficiently beyond the plane of the saw to perform efficientlyits function of bringing the surface of the quartz from which the blank,wafer, bar or section has been out into the desired plane.

Other objects and important features of the invention will appear whenthe following description and claims are considered in connection withthe accompanying drawings, in which- Figure 1 is a front elevation of amachine embodying-the apparatus features of the present invention anddesigned particularly for effecting the initial cutting of the orientedquartz or other crystal into sections, this machine being also adaptableto the cutting of the oriented quartz or other crystal into wafers ifthe latter method of preparing resonator or oscillator blanks is to bepracticed. In the machine illustrated in Figure 1, the cutting saw andsurface grinder are shown as mounted on separate shafts;

Figure 2 is a sectional plan view taken on the line 2-2 of Figure l;

Figure 3 is a plan view with the saw mounting shown in section ofanother cutting machine designed particularly for cutting the sectionsinto bars from which the final blanks are to be cut;

Figure 4 is a front elevation of the mechanism shown in Figure 3;

Figure 5 is a section on the line 5-5 of Figure 4 and shows the cutterand surface grinder assembly where these two elements are combined in asingle unit and are relatively adjustable;

Figure 6 is a sectional detail on the line 6-6 of Figure 3 showing themanner of clamping the work in the work holder employed in cutting thesections into bars;

Figure 7 is a perspective view of one of the bars after it has been cutfrom the section, the location of the optical (Z) axis, the electrical(X) axis, and the mechanical (Y) axis of the crystal being alsoindicated on this view;

Figure 8 is a front elevation of a machine designedparticularly forcutting the bars into oscillator blanks;

Figure 9 is a sectional plan on the line 9-9 of Figure 8;

Figure 10 is a plan view of the work holder employed in the machineshown in Figure 8, parts of the cutting mechanism being shown insection;

Figure 11 is a side elevation of the work holder shown in Figure 10 withparts of the cutting mechanism shown in section;

Figure 11A is a perspective view of an oscillator blank;

Fig. 12 is a plan view, partly in section, of a machine designedparticularly for grinding a true face parallel to a finished true facesuch as provided by the preceding cutting machines, and particularlyforproviding the oscillator or resonator blanks with two true faces. Thismachine can also be used for grinding true faces parallel to existingtrue faces on other quartz pieces such, for example, as sections, barsor wafers, and also for making corrections where checking has shownaccidental deviation;

Figure 13 is a side elevation of the machine shown in Figure 12;

Figure 14 is a section on the line l4l4 of Figure 15 through the workholding mechanism of the machine shown in Figures 12 and 13;

8 that do not lie in a true plane, that is, in a plane absolutelyperpendicular to the optical (Z) axis of the quartz.

As more fully disclosed in said co-pending application of W. Ford Younghereinabove identified, the universal holder 2 is constructed not onlyto have its parts locked in the adjusted relations in which the finalorientation of the tel to be oriented is preferably of such substantialconstruction that the relatively moving parts thereof may be locked inthe relation in which they stand when the quartz or other crystal hasbeen oriented and that, when thus locked, the

holder will hold the quartz with sufficient rigidity so that it may befed to the cutting saw and surface grinder without losing itsorientation. A

suitable universal holder for this purpose isonesuch as more fullyshownand described in the co-pendin'g application of W. Ford Young,Serial No. 479,609; The universal holder of said co- .pendingapplication comprises three nested rings,

the innermost ring turning about a diametrical axis on trunnions whichhave their hearing in the intermediate ring, the intermediate ringturning about a diametrical axis perpendicular to the inner ring axisand on trunnions having their bearings in the utermost ring and theoutermost ring being arranged to turn about an axis perpendicular to theplane of the ring and also perpendicular to the axis about which theintermediate ring turns.

When orienting the crystal in suitable orienting apparatus, such as thatmore fully described in said c'o-pending application of W. Ford Younghereinabove identified, the aforementioned three rings are adjustedabout their axes until the optical (Z) axis of the crystal has beendefinitely located, the crystal being fixedly held in the innermostring. If the lump or block of quartz is to be first cut into sections,as shown in Figures 1 and 2, and then into bars from which the ulti--mate oscillator or resonator blanks are to be cut, the orienting is socarried out that the universal holder 2 will present the lump or block 4of the quartz to the section cutting saw 6 of the machine shown inFigures 1 and 2 with the optical (Z) axis of the lump 4 perpendicular tothe plane of the out. From this it will be seen that when the saw 6 hasmade its out, both the cut surface on the lump 4 and that on any section8 should lie in a plane substantially perpendicular to the optical (Z)axis of the quartz, in which case both the electrical (X) axes of thequartz and the mechanical (Y) axes of the quartz would lie in this face.In practice, however, it is substantially impossible to cause a saw 6,usually of the type which has its peripheral edge and marginsimpregnated with diamonds, to maintain its perpendicularity to theoptical (Z) axis of the quartz throughout any substantial depth of cut.

This is largely due to the fact that, in order to avoid waste of theexpensive and comparatively rare quartz which is suitable forresonators, the saw disk is made of relatively thin sheet metal so thatthe cutting edge, even allowing for some clearance or set, is usuallynot over f An important feature of the present invention, as hereinabovepointed out, is to compensate for this tendency of the cutting saw 6 tolead off and thus leave both a face on the quartz block 4 and a,corresponding face on the cut-off section quartz and the determinationof the direction of the optical axis has been brought about, but thisholder is also mounted upon a slide member I 0 having a dovetailslideway adapted to fit accurately upon a carefully machined dovetailguide that will position the holder definitely and accurately both inthe orienting apparatus and in the section or wafer cutting machine. Asherein shown, the dovetail guide l2 of the cutting machine is in turnformed upon a'second slide l4 travelling on a second dovetail guide ISon which the universal holder may be fed bodily in a directiontransverse to the saw 6 to provide 'for cutting sections ofpredetermined thickness.

' As herein shown, the mechanism for effecting such transverse feedingof the lump or block 4 may be the ordinary transverse work feedmechanism for feeding work transversely to a. cutting tool, theillustrated mechanism comprising a screw I8 arranged to turn in bearings20 in the work carriage 22, this screw being threaded through a lug 24depending from the slide l4 so that turning of the screw will effectmovement of the slide I4 transverse to the saw 6.

The carriage 22 itself has threaded therethrough a feed screw 26arranged to turn in 5 bearings 28 and 30 in the frame of the cutting inthe cut face of the. lump or block 4 that may machine and to be turnedthrough suitable speed changing gearing in the housing 32, this gearingbeing driven from an electric motor 34.

By suitable manipulation of the cross feeding mechanism as, for example,by the handle 36, the holder 2, together with the lump or block 4 fixedtherein, can be fed across its longitudinal path of travel with respectto the saw 6 to provide for cutting a section of the desired thicknessfrom the quartz block 4. Feed of the block or lump 4 to the saw in thecutting operation is effected, of course, by the longitudinal feed screw26 which may be turned at the desired rate of speed to secure the bestcutting results. As is usual in feed mechanisms of lathes and millingmachines, there is provision in the gear box 32 for various rates offeed.

As hereinabove suggested, one of the most important features of thepresent invention is the provision for insuring at least one accuratelyoriented face on each section, bar, blank or wafer out. As shown inFigures 1 and 2, the face of the lump or block of quartz 4, after asection 8 has been cut therefrom, is passed over a surface grindingwheel 38 which has its abrasive face lying in a plane exactly parallelto the normal plane of the saw 6 when idling or, in other words, theplane of the abrasive face of the surface grinder 38 isexactly-perpendicular to the optical (Z) axis of the lump or block 4 asthe block is presented to the machine when it is to be cut intosectionspreparatory to cutting the sections into bars and then cutting the barsinto blanks.

In the illustrative embodiment of the invention, shown in Figures 1 and2, the surface grinder 38 is located at the right of the cutting saw 6with its abrasive surface projected sufiiciently in front of the planeof the cutting'edge of the saw 6 so that it will engage and remove anyirregularities have been left by the saw. Although separate drivingmotors l8 and 42 are shown, which are connected by V belts l4 and 46 tothe shafts on which respectively the saw 8 and surface grinder -88 aremounted, it will be understood that separate drives are not necessaryfor these two tools and that they might be driven in any suitable mannerfrom a single drive.

As brought out more fully in the co-pending application of W. FordYoung, hereinabove identified, when orienting the crystal 4 by means ofthe orienting apparatus and the universal holder 2, it is preferable, ifthe crystal is first to be cut into sections, then into bars, then intoblanks, to orient it so that not only does the optical (Z) axis have adefinite angular relation to the plane of the cut to be made in thecrystal but also one of the other axes, for example, a mechanical (Y)axis, is brought into a definite relation to the path of travel of thecrystal during the cutting and re-surfacing operations. An advantage ofthis is that it facilitates scratching a reference mark upon there-surfaced face of the lump or block 4, after the cutting and surfacegrinding opera-- when it is being cut into sections, it will be seen'that the electrical (X) axis which is perpendicular to the thus locatedmechanical (Y) axis can readily be located. As shown in Figures 1 and 2,a convenient method of doing this is to hinge an ordinary steel square48 upon the bed 58 of the machine in such manner that one leg of thesquare is parallel to the direction of movement of the carriage 22. withthis arrangement, if the face of the block or lump 4 of quartz or othercrystal be brought into a position, after it has been passed over thesurface grinder 88, where it can be engaged by the vertical leg of thesquare 48, then a scratch mark placed upon this face, by using thisvertical leg as a guide for the scriber, will correspond with anelectrical (X) axis.

As shown in Figures 3, 5 and 7, one advantage in scratching theelectrical (X) axis on the finished or true face of the section 8 cut inthe machine shown in Figures 1 and 2 is that this scratch mark on thefinished or true face, that is, the face that is absolutelyperpendicular to the optical (Z) axis, can be used in locating thesection 8 upon the glass plate 54 in such a definitely oriented positionthat when this glass plate 54 is clamped in the work holder 58 thesection will be presented to the cutting saw 58, of the machineparticularly shown in Figures 3 and 4, with the electrical (X) axis ofthe section 8 perpendicular to the plane of the cutting edge of the saw58 and with its mechanical'(Y) axis parallel to the plane of the cuttingedge of the saw 58 and its optical (Z) axis, of course, perpendicular tothe bottom or finished face of the section 8. It will thus be seen thatin the section 8 shown in Figure 3, the electrical (X) axis and themechanical (Y) axis determine a plane coinciding with the finishedbottom face of the section 8 and that the optical (Z) axis isperpendicular to this plane.

As shown in Figure 7, the bar 68, which is cut from the section 8 willalso have a finished side face, as more fully hereinafter set forth,which is in a plane determined by the mechanical (Y) axis, originallylocated in the orienting apparatus, and the optical (Z) axis, alsolocated in said orienting apparatus. The electrical (X) axis will extendtransversely of the bar 68 in a direction parallel to the bottom or trueface of the bar 88 and also in a direction which is perpendicular to theplane determined by the optical (Z) axis and the mechanical (Y) axislocated in the original orienting operation.

An important feature of the machine shown in Figure 3, as well as animportant feature of the present invention, is the combination with thecutting saw 58 used to cut the sections into bars of a concentricsurface grinder 82 mounted upon thesame arbor or spindle 64 as the saw58. It will be seen that the advantage of this arrangement is that,after the bar of quartz 68 has been cut from the section 8, the edgeface of the section from which the bar 88 has been out can immediatelybe passed over the surface grinder 62 at the center of the saw 58 andthus have its face brought into a true plane perpendicular to theelectrical (X) axis, in which plane both. the optical (Z) axis. and themechanical (Y) axis, located by the orienting step, will lie. As shown,the abrading face of the surface grinder 62pmjects slightly from theplane of the front face of the saw 58 so that, without changing thetransverse adjustment of the section 8 in respect to the saw 58, thesurface grinder 82 can remove any irregularities on the edge face of thesection 8, from which a bar 88 has been cut, that may have been left bythe saw.

In order that the aforementioned relationship between the abradingsurface of the surface grinder 82 and the plane of cut of the saw 58 canbe maintained throughout the life of the surface grinder or, in otherwords, that compensation may be madefor wear, provision is made forquickly, easily and accurately effecting such an adjustment of thesurface grinder 82 with respect to the saw 58 as will compensate for anywearing down of the abrading surface of the surface grinder 62. As shownparticularly in Figure 5 of the drawings, the arbor or mandrel 84 of thesaw 58 has keyed thereto the threaded hub 68 of a member provided with acylindrical socket 88 in which the surface grinder 82 is mounted and inwhich it may be secured in any suitable manner as, for example, by meansof cement 18. The hub 66 can be secured upon the arbor or mandrel 64 bymeans of a nut 12 engaging a washer 14 which in turn engages the bottomof the socket 88.

Threaded upon the hub 65 and adjustable thereon is a second hub 16having a similar socket-like member 18 in which the socket 68 isreceived and to the margin of which the saw 58 is secured. The disk ofthe saw 58, it will be noted, has its center cut out to receive thesocket 88. A lock nut 88 secures the two hubs 66 and 16 in theiradjusted relation to each other. Tightening of the lock nut 88 andturning of the hub 16, to effect the relative adjustment of the abradingsurface of the surface grinder 62 and the plane of the cutting edge ofthe saw 58, may be effected by suitable spanners received in sockets 82and 84, respectively in the hub 16 and in the lock nut 88.

As hereinabove pointed out, a scratch mark is preferably made upon thetrued face of the section 8 before it is cut from the lump or block 8plane which is perpendicular to the either toward arallelism to a of thequartz by the cutting machine shown in Figure 1, this scratch mark beingmade usually by guiding the scratching diamond along the edge of thevertical leg of the square 48 in Figure 1. This scratch mark is thenused to locate or orient the section 8 upon a glass plate 86. Thesection 8 is cemented to the plate 86 after it has thus been accuratelyoriented.

The purpose of the glass plate 86 is twofold: (a) it provides means bywhich the section 8 to be cut into bars 68 can be secured rigidly in thework holder in proper oriented relation to the saw; (17) it preventschipping of at least one edge of the quartz during the bar-cuttingoperation and also prevents prematur breaking off of the bar from thesection; the glass plate usually extending to some distance to each sideof the section 8.

From theforegoing it will be seen that, if the edge of the glass plate86, which is usually bevelled to fit into a dovetailclamping groove 88in" the work clamping part of the work holder 88, be used as a referencemark in orienting the quartz section 8- in the holder 88, the dovetailgroove 88 being held accurately in a horizontal vertical lane of thecutting edge of the saw 58 and having its side recess, which receivesthe bevelled edge of the glass 86, also perpendicular to the plane ofthe cutting saw 58, then both the true face of the section 8, that is,its bottom face which lies against the glass plate 86, and theelectrical (X) axis, which has been scratched upon the true face of thesection 8, can be definitely and accurately oriented in respect to thesaw 58. This can be done merely by mounting the section 8 upon the glassplate 86 with its true face against the upper face of the glass 86 andthe scratch mark, showing the direction of the electrical (X) axis,parallelito the bevelled edge of the lass plate.

hereinabove suggested, it is also customary, andjit, is likewiseimportant that the direction on the bar'68 in which an original major orminor apex face of the crystal was located be indicated. This maybedone, as above suggested, by marking on the section 8 an arrow 82pointing in the direction of the apex face to be considered, here aminor face. As is well known, blanks for resonators or oscillators whichare to have substantially a zero temperature coefilcient are usually cutat an angle to the optical (Z) axis which causes them to be inclined tothe said optical (Z) axis major apex face or toward parallelism to aminor apex face. Thus, if the direction of a major face be marked uponthe section 8 and then appear also upon the bar 68, it facilitatesproperly in the machine in which it is to be cut into sections inclinedto the optical axis, either for an AT or a BT cut.

As shown in Figures 4 and 6, one side of the dovetail groove 88 whichreceives the glass plate 86 comprises a movable member 84 which may bepressed into clamping relation to the bevelled edge of the glass plate86 and thus force the other edge into accurately oriented relation tothe fixed side of the groove 88. This may be done my means of a milledclamp nut 86 on a bolt 88 extending through the work holder 88, the nut86 having a rounded inner end engaging the clamp member 84 and the rod88 having a rounded head I88 engaging the end of the opening I82 throughthe holder 88 in order to provide the required freedom of adjustmentpositioning the bar 68 pointer I 24.

p 5 necessary to prevent breaking of the-edge of the glass plate 86during the clamping operation.

The work holder 88, in which the glass plate 86 with the section 8mounted thereon is clamped, is itself mounted on a carriage I84 movableparallel to the plane of the saw 58, the work holder 88 being movable onthe carriage I 84 transversely to the plane of the saw and beingaccurately guided in its transverse movements by a dovetail I86 receivedin a similarly shaped guideway I88 in the carriage I84. The movement ofthe work holder 88 on the carriage I84 transverse to the plane of thesaw 58, in order to feed a width of the section 8 into position to becut into a bar 68, can be brought about in any suitable manner. Asherein shown, this adjustment is usually effected by hand, a clamp screwII8 being arranged in accessible position to clamp the work holder 88 inits adjusted relation to the carriage I84. To facilitate the transverseadjustment, "so, that bars 68 of predetermined and uniform width may beout, a stop member II2, pivoted at I I4 to swing on the stem I I6 of agage screw I I8, can be swung into. position so that the finished faceof the section 8 will strike this stop, the setting for the desiredwidth being predetermined in any suitable manner as, for example, byproviding the milled head I28 of the gage screw with graduations I22'tobe read in respect to a The section 8 having been cut into bars 68 inthe manner hereinabove described, it will be seen that, by the procedureso far described, each of these bars 68 will be provided .with two ac-,curately oriented faces, one being its part of the original accuratelyoriented face of the section 8, this face of the bar 68 being the onenext to the glass plate 86, and the other accurately oriented face beingone of the side faces of the bar 68, namely, the one that has beenground upon the edge face of the section 8 from which the previous bar68 has been cut, this grinding being done, as hereinabove pointed out,by passing the edge face of the section 8 over the surface grinder 62after the saw 58 has cut ofi the previous bar 68. It will thus be seenthat each bar 68 is provided with two very accurately oriented faceswhich may be used in mounting it inthe work holder of the machine inwhich the bar 68 is to be cut into blanks for oscillators or resonators.

If only one bar 68 is to be cut into blanks at a time it is usually notnecessary to provide further accurately oriented faces on the bar 68before mounting it upon the glass Plate I26 by means of which it can beheld in the work holder and accurately oriented in respect to thecutting saw I28 and the surface grinder I88 of the blank cuttingmachine. Since, however, it is usually desirable to mount more than onebar 68 on the glass plate I26 of the blank cutting machine, so that twoor more blanks may be cut at each cutting operation, it is sometimesdesirable, in order to facilitate the orienting of the two bars inrespect to the glass plate I26 and in respect to each other, to provideat least one of the bars with two accurately oriented side faces. Thiscan readily be done, as will appear more fully hereinafter, by the useof the machine shown in Figures 12 and 13. As more fully describedhereinafter, in this machine a face parallel to 7 any true face may beground upon a section, bar

or blank by mounting the true face against the made.

work-locating face of the work holder of the machine and then passingthe other face over a surface grinder which has its abrasive surface ina plane parallel to the work-locating face of the work holder.

If, as shown in Figure 9, it is desired to out two blanks at eachcutting operation of the blank-cutting machine, then it is usuallypreferable to grind another true side face on one at least of the bars60 which'is parallel to the true side face provided on said bar asamincident to the bar-cutting operation. The two bars may then bemounted on the glass plate I26 with a lateral true face of the one baragainst a lateral true face of the adjacent bar and with both of the toparrows 92, indicating the direction of a minor apex face, pointing inthe same direction, this direction varying according to the cut to be Ashereinabove pointed out, however, blanks for resonators or oscillatorsthat have a substantial zero temperature coefiicient are usually cut atan angle to the optical axis, one of the most common types of blanksshowing such zero temperature coefficient characteristic being made bythe so-called BT cut and the angle of this cut usually being in theneighborhood of 49 to the optical axis.

The work holder for the blank cutting machine comprises, in theillustrative embodiment, a casting I32 having a machined face I34inclined to the plane of the saw I28 and also to the plane of thesurface grinder I30 substantially at the desired angle of the cut to bemade. Since, in the bars 60, the optical (Z) axis is perpendicular tothe bottom true face of the bar, this gives the desired inclination ofthe face of the oscillator blank to the optical axis. As hereinabovepointed out, the mechanical (Y) axis of the crystal extends lengthwiseof the bar 60 and the electrical (X) axis extends transversely to thelength of the bar or, in other words, it extends parallel to the planeof the saw I28 when the bar is in the position shown in Figures and 11.

To permit such slight adjustments as may be necessary to correct anydeviation from the original accurate orientation which may havebeenbrought about either in the intermediate bar cutting operation or in themounting of the bar 60 on the glass plate I26, the work holder I32 ispivoted at I36 upon a support I38 so that its inclination to the planeof the saw I28 may be varied slightly. To permit quick adjustment of theinclination of the work holder I32, a cam shaft I40 has its bearings inthe support I36 and engages the under side I42 of the holder I32 toincrease of decrease the inclination of the holder I32 to the plane ofthe saw I28 as the cam I40 turns. A strong spring I44 connected at I46to the base of the support I38 and connected at I48 to the under side'ofthe holder I32 tends to hold the holder I32 tightly against the camshaft I40.

After the first oscillator blank is cut from the bar or bars 60 in themanner shown in Figures 10 and 11, it is checked in any suitablegoniometer to determine whether or not the inclination of its true faceto the optical axis is correct and also to determine whether or not theelectrical or (X) axis is also properly directed. In other words, theblank is checked for what are commonly referred to as the A and "Bangles, the A angle being the angle between the (X) axis of the mothercrystal and the intersection of the crystal face and the XY plane, andthe B angle being the angle which the crystal face makes with the XZplane.

The adjustment just described is for the purpose of compensating for anyvariation of the cut from the desired B angle. To facilitate thisadjustment a scale I50, concentric with the axis of the cam shaft I40,is graduated in minutes and a pointer I52, connected to the cam shaftand moving over the scale, permits the operator to determine at once,after the variation from the desired B angle has been ascertained, howmuch of an adjustment is necessary to correct this variation.

It will also sometimes happen, in mounting the bars 60 on the glassplate I26, that there is an accidental deviation from the desired Aangle. This angle can alsobe checked in the goniometer readings from thefirst blank cut from am! bar 60 and adjustment be made to compensate forany variation from the desired A" angle.

The illustrated means for compensating for any variation from the A"angle which may be found when the first blank cut is checked in thegoniometer, comprises a normally fixed guide bar I54 for the glass plateI26, said bar I54 being pivoted at I56 on the upper face I34 of theholder I32. The bar I54 is secured to the face I34 by machine screwsI58, the stems of which extend through arcuate slots I60 so that the barI54 may be rocked about its pivot I56 to a limited extent to permit suchswinging of the crystal bars 60 in the plane of the upper face I34 ofthe work holder asmay be necessary to compensate for any variation fromthe desired A angle that may have been found when checking the firstblank cut. In order that this adjustment also may be made directlywithout any trial and error procedure, an adjusting screw I62 isthreaded through a lug I64 near the upper end of the bar I54. The screwI62, having its bearings in the member I66, serves to cause the bar I54to swing in either direction about its pivot I56 when the clamp screwsI58 have first been loosened. A pointer I68, cooperating with theperipheral scale I10 on the head I12 of the screw I62, permits theoperator to read directly the amount of compensating adjustmentnecessary to correct any deviation from the desired A" angle which maybe found in checking the first blank cut.

From the foregoing it will be seen that provision is made for quicklyinsuring the proper positioning of the bars 60 in respect to the saw I28in the blank cutting machine of the present invention in the event thatslight deviations from the desired A and BT angles have come abouteither through mounting or otherwise. It may be said, however, thatordinarily, substantially no adjustment isrequired and that, even ifadjustment be required, the first blank cut can usually be corrected inthe machine hereinafter to be described so that it will be usable.Furthermore, ordinarily after checking the first blank and making therequired adjustments, it will be found that the second blank out hasboth its A and B angles practically on the nose and therefore no furtherchecking is necessary. This greatly facilitates the production of blankssince, in this machine as in the operation of the machines shown inFigures 1, 2 and in Figures 3 and 4, after each blank H3 is cut from thebar 60 the bar is provided with a true or properly oriented face bypassing it over the surface grinder I30. Therefore, each blank II3 cutfrom the bar 60 has one accurately oriented face which can be used inthe machine now to be described for providing the blank with anotheraccurately oriented face.

The feedin of the bars 60 to the cutter I28 may be effected in anysuitable manner as, for example, by the usual milling machine feed screwI14 and the feeding of the bars 60 transversely to the cutter I28, tocut blanks I13 of the desired thickness, is preferably done by hand. Tofacilitate insuring uniform thickness, a stop I 16 is provided whichcomprises a machine screw threaded through the frame I18 of the cuttingmachine and so positioned at one side of the saw, as shown in Figure 9,that the resurfaced ends of the bar 60 may be brought into abuttingrelation to this screw and then clamped in this relation to insure thecutting of blanks I13 of the desired thickness and orientation; Tofacilitate such adjustment, the head I80 of the screw I16 is providedwith thickness graduations I82 which may be read in respect to a pointerI84.

To permit the resurfaced ends of the bars 60 to be brought into abuttingrelation to the screw I16, the glass plate I26, on which the bars 60 aremounted, may be unclamped so that it can slide along the fixed guide I54which, after any required adjustment to compensate for variation fromthe desired A angle, has been locked in this adjustment by the setscrews I58. The guide bar I54 has an overhanging bevel which engages thebevelled side of the glass plate I26.

Another movable guide and clamping bar I86 with a similar overhanginbevel, engages the other bevelled edge of the glass plate I26. The

guide bar I86 is movable on guide pins I88 into and out of clampingrelation to the glass plate I26.

vA clamping bolt I90, having arounded head fittedinto a rounded socketin the clamping bar I86, is provided at the other side of the frame witha wing nut I92 by which the bar I86 can quickly be brought into clampingrelation to the glass plate I26 and as quickly released. By unscrewingthe nut I92 the glass plate I26 may be permitted to slide down intoabutting relation to the stop I16 and then secured in this relation,thus insurin the cutting of blanks of substantially uniform thickness.

In each of the machines thus far described which have provision forgrinding a true face,

on the section, bar or blank before it is cut from the lump, section orbar it will be obvious that the relative movement of the work to beground and the grinder need not be at the same rate of speed as therelative movement of the work to be cut and the saw. To avoid any delayin production it is therefore sometimes advantageous either to providefor a change of speed in the feeding mechanism when the Work is beingpassed over the surface grinder or to disconnect the mechanical feed andeffect the surface grindin feed by hand. i

From the foregoing description it will be seen that, in each step of theprocess so far described the section, bar or blank, cut respectivelyfrom the lump, section or bar of quartz or other crystal, is providedwith at least one accurately oriented face before it is cut from thebar. This may not, of course, necessarily be true of the first blankcut, as above explained, because of accidents or carelessness inmounting on the glass plate I26, but even such blanks, after checking,can readily have true faces restored in the machine presently to bedescribed. However, if the section, bar or blank has one true face it isa simple matter to provide it with another true 'face. This may be donein the machine just referred to which'is shown in Figures 12 to 17inclusive.

In the machine shown in Figures 12 to 17 inclusive, a wheel I94 mountedon a rotatable shaft I96, having its lower bearing in the main frame I98of the machine and its upper bearing in the gooseneck 200, carries aplurality of work holders 202 which carry the work in a horizontal plane'(ver the face of a surface grinder 204 driven by a suitable motor 206.The rotation of the wheel I94 to effect the movement of any work holder202 in the direction to carry its work over the abrasive face of thesurface grinder 204 is preferably effected by hand and may comprise anoscillating movement to carry the work over the grinder first in onedirection and then in the other direction.

To hold the work, such as a blank, bar or section, upon the work holder,in order to effect the grinding of a face on the work parallel to anaccurately oriented face, suction means are provided. As herein shown,particularly in Figures 14 and 17, each work holder 202 has an underface 208 which, in its normal adjustment, lies in a plane exactlyparallel to the abrasive surface ofthe surface grinder 204. Also, asherein shown, each holder 202 has, opening through this face 208, threesuction openings 2I0, 2I2 and 2I4, communicating with any suitablevacuum pump, such communication being preferably made by means offlexible vacuum hose 2I6 to permit free oscillation or turning of thewheel I94;

In the form of the work holder shown in Figure l4, vacuum for thesuction opening 2I0 is provided through a connecting pipe 2I8 controlledby hand valve 220. Similarly vacuum for the suction opening 2I2 isprovided through a branch pipe 222 controlled by a valve 224 and vacuumfor the suction opening 2I4is provided through a branch pipe 226controlled by valve 228.

As above suggested, when the work holder 202 is in its normal adjustmentthe under face 208 thereof is absolutely parallel to the surface grinder204 so that, if a blank I13, for example, which is to be provided with asecond true face, has one true face, then by simply putting that trueface against the surface 208 the operator can be assured of havinganother true face ground upon the side of the blank adjacent to thesurface grinder 204, when the face 208 of the holder 202 is in itsnormal position of adjustment in which it is parallel to the plane ofthe abrasive surface of the grinder 204.

When, however, it is desired to use the machine illustrated in Figures1'2 .to 17 for correcting the initial check blanks, it is desirable tomake provision for inclining the face 208 in respect to the plane of theabrasive surface of the surface grinder 204 in order to provide for anyvariation which the resurfaced face of the check blank may show from thedesired A and/or B angles. In the illustrative embodiment of theinvention, the main body 232 of the work carrier, which may be fastenedupon the rim of the wheel I94 as shown in Figure 15 by any suitablemeans such as a clamp screw 234 and through bolts 236, is provided witha guideway 238 in which the work 'quired to hold the work inplace.

through which an adjusting screw 244 is threaded, this screw beingmounted in a bearing 246 on the carrier frame 232 and having a graduatedhead 248, the 'work thickness graduations of which may be read inreference to a pointer 2 0.

Fulcrumed upon a pivot 252 screwed into the vertical slide 240 is thework holder proper 202, in the bottom face 208 of which the suctionopenings 2l0, 2I2 and 214 are provided. In order to effect angularadjustment of the work, holder 202 about the pivot 252, the upwardlyextending arm254 of this work holder is provided with a swivel 256,having its bearing in the upper end of said arm and through the squaredhead of which is threaded an adjusting screw 258 having a bearing in theslide 240 and having a graduated head 260, the angle graduations ofwhich can be read in reference to a pointer 262.

From the foregoing description it will be seen that by verticaladjustment of the slide 240, the.

thickness to which it may be desired to reduce any section, bar or blankwhen grinding a second true face parallel to the original true face, canreadily be predetermined. It will further be seen that by the angularadjustment of the work holder 202 the work positioned against the face208 can be tilted to such an angle to the plane of the surface grinder204 that correction of any variation from the A or B" angles which maybe found, for example, in the check blank first cut from a bar in themachine shown in Figures 8 to 11 inclusive, may readily be corrected.

In Figure 17 is shown modified valve-controlling means for controllingthe application of the suction to the respective suction openings H0, H2and 2| 4. It will be apparent that, when finishing blanks, that is,providing each blank with a second true face parallel to the first,these blanks having relatively small face areas, for

example, x or 74" x 3.4", only one suction opening will be required tohold the work in place. For larger pieces of work, such as bars andsections, suction applied to the work from either two or three of theopenings may be re- In the form of the work holder shown in Figure 17,instead of using separate valve controls 220, 224 and 228, as shown inFigure 14, the valves 264, 266 and 268 are in the form of slidingcylinders of different widths mounted on a common shaft 210 slidingthrough a stuffing box 212. On the shaft 210 is an operating handle 214.An indicator 216, pivoted at 218, and having a pointer passing over achart 280 is moved by the handle 214 to indicate on the chart both theoff position in which all three suction openings are closed and thepositions in which either one, two or three of the I suction openings2I0, 2I2 2|4, are in working condition.

From the now completed description of the novel procedure of the presentinvention which is carried out in the manufacture of resonator oroscillator blanks that have their faces and edges properly oriented, itwill be seen that, from the time the initial orientation has beeneffected, throughout each Succeeding cutting operation there is verylittle opportunity for the orientation to be lost. This has beeneffectively demonstrated in the manufacture of thousands'of accuratelyoriented blanks. It will further be ,seen that substantially the onlysteps in the manufacture of the resonator or oscillator blank whichrequire any special skills are the original orientation, thepreferredinethod of which, more fully disclosed in the co-pendingapplication of W. Ford Young, Serial No. 479,509, filed March 18, 1943,is not in itself a part of'the present invention, and in the checking ofthe A and B" angles of the first oscillator blank cut from the bars 60in the machine shown in Figures 8 to 11, inclusive, to be sure that theoriginal orientation has notbeen disturbed in the mounting of the bars60 on the glass plate I26. Except for these two steps, which requiresome knowledge of the relationship of the faces of the oscillator blankto the original axes of the mother crystal, all other operations can beperformed by comparatively unskilled labor.

With such unskilled labor, supervised only as to the orientation andchecking, oscillator blanks can be cut on a large scale production basiswith a minimum waste of the quartz, which blanks can consistently bekept within 5 minutes of either the A angle or the 3" angle, which iswell within the tolerances allowed for blanks that are to be finishedinto piezo-electric oscillators having definite frequencies andsubstantially zero temperature characteristics.

What is claimed as new is:

1. The process of cutting quartz or other crystals which exhibit thephenomenon of piezo-electricity, in the manufacture of piezo-electricoscillators, which consists in so orienting a crystal block from which asection, bar, blank or wafer is to be cut and so fixing said block inparallel-feeding relation to the crystal-cutting saw that throughout thesuccessive relative cutting movement of the block and saw required tocut a plurality of sections, bars, blanks or wafers from the block, theoriented axes of said block bear the desired predetermined angularrelations to the plane in which the cutting edge of said saw travelswhen moving idly, effecting the relative cutting the'said block fixed inthe same parallel feeding relation to said plane, passing the cut faceof the block over an abrading tool which has its abrading face movablerelatively to said block in a plane parallel to the aforementioned planeof idle movement of the cutting edge of said saw, in order to removeirregularities in said freshly cut face of said block which may havebeen caused by any deviations of said saw, during the cutting operation,from its aforementioned plane of idle movement, whereby at least oneface of each succeeding section, bar, blank or wafer cut from the blockwill be in a true plane to which its axes will bear 4 the aforementionedpredetermined angular relaions.

2. A process according to claim 1 in which the crystal block is quartzand is fixed in its parallelfeeding relation to the crystal-cutting sawwith its optical (Z) axis perpendicular to the plane of idle movement ofthe cutting edge of said saw.

' 3. A process according to claim 1 in which the crystal block is quartzand is fixed in its parallelfeeding relation to the crystal-cutting sawwith a mechanical (Y) axis parallel to the direction of the feedingmovement thereof.

4. A process according to claim 1 in which the crystal block-is quartzand is fixed in its parallelfeeding relation to the crystal-cutting sawwith with an electrical (X) axis perpendicular to the direction of thefeeding movement thereof.

5. Apparatus for use in cutting sections, bars, blanks or wafers from ablock of oriented crystal in the manufacture of piezo-electrlcoscillators which comprises a holder in which said crystal block may befixed in the desired oriented relatlon to the plane of the idle movementof the cutting edge of the crystal-cutting saw, said holder havingprovision for adjustment of said block across the said saw planewithoutdisturbing its oriented relation thereto to permit cuttingtherefrom pieces of the desired thickness. and means for effecting arelative work feeding movement of said saw and said holder in directionsparallel to said plane to eii'ect the cutting of said pieces from saidblock, and a surface grinder so located in an extension of the path ofrelative feeding travel of said block and said saw as to engage the faceof the block from which a piece has been out. after the cuttingoperation has been completed, the abrading face of said surface grinderlying in a plane parallel to the plane of the idle movement or thecutting edge of said saw.

6. Apparatus according to claim in which the surface grinder isconcentric with the saw and is mounted on the same shaft.

7. Apparatus according to claim 5 in which the surface grinder isconcentric with the saw, is mounted on the same shaft and has itsabrasive face in a plane slightly raised from the plane of,

the cutting edge of the saw.

8. Apparatus according to claim 5 in which the surface grinder isconcentric with the saw. is mounted on the same shaft and has its Iabrasive face in a plane slightly raised from the plane of the cuttingedge of the saw and in which means are provided for effecting a relativeadjustment of said saw and said surface grinder to compensate for anyvariation in said plane relations due to wear.

9. A combined saw and surface grinder for the A purposes described,comprising a circular saw and surface grinder concentrically arrangedand interconnected, the abradingsurface of the surface grinder beingraised slightly from the plane of the cutting edge of the saw and thecombined structure having means for effecting a relative adjustment ofthe saw and surface grinder along the common axis thereof to compensatefor wear of the abrading surface of the grinder.

10. Apparatus according to claim 5 in which the block holder comprisesparts relatively adiustable to bring the crystal block held thereby intothe desired oriented relation to the plane of the idle movement of thecutting edge of the crystal cutting saw and also comprises means forlocking the relatively movable parts in this adjusted relation.

11. Apparatus according to claim 5 in which the work holder has a worksupporting face normally inclined to the plane of the saw at the dementof the work in the plane of the inclined face of the said work'holder tocompensate for errors in orientation in respect to the A" angle of theoscillator blank.

13. A combined saw and surface grinder for the purposes describedcomprising a circular saw and a circular surface grinder concentricallyarranged and interconnected, said surface grinder comprising an abrasivesurface and a circular support therefor of sufficient axial-thickness toform a solid, inflexible backing for said abrasive surface andalsoconstitute a supporting hub for the saw, and said circular sawcomprisinga relatively thin, easily flexed, disk having a narrow cuttingedge and being of sutliciently greater diameter than the circularsurface grinder to permit complete severance of each piece to be cutsuccessively from a block or the like before the cut face of the blockcomes into engagement with the surface grinder, said saw being somounted on said relatively thick hub that the abrading surface of thesurface grinder is raised slightly from the side of the plane of thecutting edge of the saw adiacent to the cut face of the block, wherebyany deviation of the face of the block from said plane, resulting fromwandering of the relatively thin, easily flexed saw, may be corrected bysaid inflexibly mounted surface grinder.

MARCUS RAMSAY.

